Power semiconductor devices such as IGFETs (insulated gate field effect transistors) as well as DMOS (diffused metal oxide semiconductor) portions of smart power semiconductor devices including both power transistor cells and logic circuits are typically based on transistor cells formed along stripe-shaped electrode structures which run through a transistor cell area. In an on-state a load current flows in a vertical direction through semiconductor mesas between the electrode structures. In a blocking mode the electrode structures deplete drift zone sections in the semiconductor mesas such that a high blocking capability can be achieved even at a comparatively high dopant concentration in the drift zone sections that in turn ensures a low on-state resistance RDSon of the transistor cells.
It is desirable to improve the reliability of power semiconductor devices.